From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5EAA3CA0EED for ; Wed, 20 Aug 2025 09:35:20 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 003CB8E004A; Wed, 20 Aug 2025 05:35:20 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EF6C06B0124; Wed, 20 Aug 2025 05:35:19 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E0CD78E004A; Wed, 20 Aug 2025 05:35:19 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id CCDB16B0123 for ; Wed, 20 Aug 2025 05:35:19 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 9F74B1179D6 for ; Wed, 20 Aug 2025 09:35:19 +0000 (UTC) X-FDA: 83796627558.08.5A75C8A Received: from mail-ed1-f66.google.com (mail-ed1-f66.google.com [209.85.208.66]) by imf19.hostedemail.com (Postfix) with ESMTP id A9C061A0009 for ; Wed, 20 Aug 2025 09:35:17 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=RWwQKJES; spf=pass (imf19.hostedemail.com: domain of memxor@gmail.com designates 209.85.208.66 as permitted sender) smtp.mailfrom=memxor@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1755682517; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=wNVeEm5XhdBpT7eUdLFg7DGJnmMc3Txy3EfKiydyTJk=; b=JgjjnX6R97R1qDwDPIID1tX5Y5p/OAUV3J1MuWtqFVzYnIvG/HMIyFasqj3Iie91n0xq+m SIu+fBb8Lsax0O/Zzn55IE3YlFf8sk6kKOnq/BJZvxIsdZw1DZiTLAMwduk4qkKkbW8CpH S6pa96todupyYx9jWSCN9chKMP9eHOU= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=RWwQKJES; spf=pass (imf19.hostedemail.com: domain of memxor@gmail.com designates 209.85.208.66 as permitted sender) smtp.mailfrom=memxor@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1755682517; a=rsa-sha256; cv=none; b=b4Etb3lQj79dwXbs04uw1e0NiPkoQ5uhguVNiF1X31osglz/H9EVKCpJfsbPRp8CGIuCMy 1jzwdU8ljyeqtEaHNhCvmAovaNYVAETX3euqgiT1+VIH0OphyrM/l1Ju3hsu2W+YB5m1hq l75AWfGhkW7ad/AKLblLv75Nks2DZEI= Received: by mail-ed1-f66.google.com with SMTP id 4fb4d7f45d1cf-61a2a5b0689so6324780a12.1 for ; Wed, 20 Aug 2025 02:35:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1755682516; x=1756287316; darn=kvack.org; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=wNVeEm5XhdBpT7eUdLFg7DGJnmMc3Txy3EfKiydyTJk=; b=RWwQKJES+i5iL+zIN6jekq7KBhQrootJJkdAlaqAZj69TQSEfG2tRe5BWi5DXnKV/A C2Pnhi493ZjN0QC2L0ciDtZCQG7K2pnaIMlThhHeSDUSncapqUSEX24L83e+RMQIw/H+ K35ZJGW56OMtKM+1xXdkOYK5BXY0zY/YRnuv09z8HZQdCdi9AGEv1WvSVjnXr6c3Jahu cioUxN4Dd9P3aIDKbr+d6zEdQ7zAfQeTP3L6VKbvl4QjTK+12Gybu1uJiW3Q4Oll30FS NFiM6KpYIwOGD43IkODAsAKpuaNO95CWA67CpZ3k+8VOcJdOaOpPSt9AHrneNuEJJvMX XfHw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1755682516; x=1756287316; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=wNVeEm5XhdBpT7eUdLFg7DGJnmMc3Txy3EfKiydyTJk=; b=sci4187gRtiTIrfGp86jZ/4EcscXHuZZxCeOx1PU8EMjca6ZCH3EiREKyLM9bwIjSA bDExl2os7KU9llycdHmki3LnbeY682as6i5fjtRKzn69ZhgSUfsZWN3IKalxMsi3CN7u Yqx/AxNVbOZyZL5P/t071+2qAlH8MBdD/VTwSSmErMmRl/XtOzD0U1f4QgUbq6rZoV45 RhIJTx3i/bodSyc+Lkrykk254ibDX6Sz2h+p0lY+drlKNvqrWOlNjTEHoRDCBoVgYJLQ iYO00LURKXJytdgx7T6EyTRLUTJyCl8pqEhn8pkWap8ko00Ez88uUkIif+eL0ednQdIO 45gg== X-Gm-Message-State: AOJu0Yy/13MKsbR3sJ6vTNoB9KXS9bxVb3LpluFPNNFq7xkFZ6EKQhYZ R6JokpIVcyDh5YcC8SUY4Dp/ByyHL7McVyZMkdiBrDUJuJ7dunfxltT81ZiV6s7wyNbbQXe8KTi RAX0xlvXpLLD8DYz8vU1V30HeDkVGkzw= X-Gm-Gg: ASbGncvevFAT/zzGwHHdZoNYMvOfq40APSih2O8zHQH0XNlFH9JFGkGQZSQKkxm4+fI BJDIi3r6SxIHuy3tKYNlH9zeU5xXyv+T8RyJBL5uqgMJBc0LuPgJKdWoeLFBLr4gGR48aJ7sM9/ 9C6CGq5golM9WEgujrPoINykiNN5uP7f2qjR7rkEDDTaIir4FbKku2D3FU4RvkMMwSJ8a0TEx4y pZUlXmd2LhVI0VfOz7n X-Google-Smtp-Source: AGHT+IHBth0y2AoBjyW+FSstnXpJk7GFg8YiBsBpirEqa2CurHSrua29TJ4cbd0mGJpW+ZWyp820YdytDUDw2fC5XFs= X-Received: by 2002:a05:6402:524c:b0:615:274e:6509 with SMTP id 4fb4d7f45d1cf-61a9754e59emr1633953a12.9.1755682516017; Wed, 20 Aug 2025 02:35:16 -0700 (PDT) MIME-Version: 1.0 References: <20250818170136.209169-1-roman.gushchin@linux.dev> <20250818170136.209169-7-roman.gushchin@linux.dev> In-Reply-To: <20250818170136.209169-7-roman.gushchin@linux.dev> From: Kumar Kartikeya Dwivedi Date: Wed, 20 Aug 2025 11:34:39 +0200 X-Gm-Features: Ac12FXxn2NcyTwhNtOzVYKNCNtBqfk-dMrPX2NDgw7posh_y0GfGmoA2HZDRcuA Message-ID: Subject: Re: [PATCH v1 06/14] mm: introduce bpf_out_of_memory() bpf kfunc To: Roman Gushchin Cc: linux-mm@kvack.org, bpf@vger.kernel.org, Suren Baghdasaryan , Johannes Weiner , Michal Hocko , David Rientjes , Matt Bobrowski , Song Liu , Alexei Starovoitov , Andrew Morton , linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: sxgndiitsm9brb8ypp5p94ndncjihgru X-Rspam-User: X-Rspamd-Queue-Id: A9C061A0009 X-Rspamd-Server: rspam01 X-HE-Tag: 1755682517-931878 X-HE-Meta: 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 Rynhyx4M 2hAzm+dBSYJWJZsixNnDIIyuo8NALVN33GNRcJFOSYYwPp/oJjtB8v8n8Onp2o2c8nUce1XzrI/yjevbeowGEFUPXt/PfmJ+bb2yc/X2Jyo67NhYRUVQK/lIYumw5z98LQj5jcm0A2SacmIPbRn1DLV7nxp/He5gdwMSFvqBqP1Y6AYn8y4tfozXi+gR1pfBkA+wXQlJawk2XWaIhjL48ORXTlY2BJi+oJUkeoZf6JHzUpfm7nb4X82j/Lc/DhravGNVvQEOi8zmRJxl2wU0fBOx0NKNT13eOyVUhu43tLA8Rdr1Yv+fyXFwVwvXuZ4zmq3RhKrgm7OVsqc1gA09z3gtiO5kY3KKrXBpJpHcK/y9jNwBZHx9rpjvLUD+lZEflHML+4esZ+ZVKioo9CRF1UN1X2DuYwyZ+ntAPX/mIyYqKYgXnJjO0Q5TmfCP0I9tpVNH+uwD9GjuMTNlUy1ssOYNCBRfCLSBpsySzorU4Gc4hZfWNULvcV6GbkW6ny3o0zAasLbgGhQN2E3c= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 18 Aug 2025 at 19:02, Roman Gushchin wrote: > > Introduce bpf_out_of_memory() bpf kfunc, which allows to declare > an out of memory events and trigger the corresponding kernel OOM > handling mechanism. > > It takes a trusted memcg pointer (or NULL for system-wide OOMs) > as an argument, as well as the page order. > > If the wait_on_oom_lock argument is not set, only one OOM can be > declared and handled in the system at once, so if the function is > called in parallel to another OOM handling, it bails out with -EBUSY. > This mode is suited for global OOM's: any concurrent OOMs will likely > do the job and release some memory. In a blocking mode (which is > suited for memcg OOMs) the execution will wait on the oom_lock mutex. > > The function is declared as sleepable. It guarantees that it won't > be called from an atomic context. It's required by the OOM handling > code, which is not guaranteed to work in a non-blocking context. > > Handling of a memcg OOM almost always requires taking of the > css_set_lock spinlock. The fact that bpf_out_of_memory() is sleepable > also guarantees that it can't be called with acquired css_set_lock, > so the kernel can't deadlock on it. > > Signed-off-by: Roman Gushchin > --- > mm/oom_kill.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 45 insertions(+) > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index 25fc5e744e27..df409f0fac45 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -1324,10 +1324,55 @@ __bpf_kfunc int bpf_oom_kill_process(struct oom_control *oc, > return 0; > } > > +/** > + * bpf_out_of_memory - declare Out Of Memory state and invoke OOM killer > + * @memcg__nullable: memcg or NULL for system-wide OOMs > + * @order: order of page which wasn't allocated > + * @wait_on_oom_lock: if true, block on oom_lock > + * @constraint_text__nullable: custom constraint description for the OOM report > + * > + * Declares the Out Of Memory state and invokes the OOM killer. > + * > + * OOM handlers are synchronized using the oom_lock mutex. If wait_on_oom_lock > + * is true, the function will wait on it. Otherwise it bails out with -EBUSY > + * if oom_lock is contended. > + * > + * Generally it's advised to pass wait_on_oom_lock=true for global OOMs > + * and wait_on_oom_lock=false for memcg-scoped OOMs. > + * > + * Returns 1 if the forward progress was achieved and some memory was freed. > + * Returns a negative value if an error has been occurred. > + */ > +__bpf_kfunc int bpf_out_of_memory(struct mem_cgroup *memcg__nullable, > + int order, bool wait_on_oom_lock) I think this bool should be a u64 flags instead, just to make it easier to extend behavior in the future. > +{ > + struct oom_control oc = { > + .memcg = memcg__nullable, > + .order = order, > + }; > + int ret; > + > + if (oc.order < 0 || oc.order > MAX_PAGE_ORDER) > + return -EINVAL; > + > + if (wait_on_oom_lock) { > + ret = mutex_lock_killable(&oom_lock); > + if (ret) > + return ret; > + } else if (!mutex_trylock(&oom_lock)) > + return -EBUSY; > + > + ret = out_of_memory(&oc); > + > + mutex_unlock(&oom_lock); > + return ret; > +} > + > __bpf_kfunc_end_defs(); > > BTF_KFUNCS_START(bpf_oom_kfuncs) > BTF_ID_FLAGS(func, bpf_oom_kill_process, KF_SLEEPABLE | KF_TRUSTED_ARGS) > +BTF_ID_FLAGS(func, bpf_out_of_memory, KF_SLEEPABLE | KF_TRUSTED_ARGS) > BTF_KFUNCS_END(bpf_oom_kfuncs) > > static const struct btf_kfunc_id_set bpf_oom_kfunc_set = { > -- > 2.50.1 >